The XtPopupSpringLoaded function performs
exactly as XtPopup except that it sets the shell spring_loaded field
to True and always calls XtAddGrab with exclusiveTrue and spring_loadedTrue.

The XtCallbackNone, XtCallbackNonexclusive, and XtCallbackExclusive
functions call XtPopup with the shell specified by the client data
argument and grab_kind set as the name specifies. XtCallbackNone, XtCallbackNonexclusive,
and XtCallbackExclusive specify XtGrabNone, XtGrabNonexclusive,
and XtGrabExclusive, respectively. Each function then sets the widget
that executed the callback list to be insensitive by using XtSetSensitive.
Using these functions in callbacks is not required. In particular, an
application must provide customized code for callbacks that create pop-up
shells dynamically or that must do more than desensitizing the button.

MenuPopup
is known to the translation manager, which must perform special actions
for spring-loaded pop-ups. Calls to MenuPopup in a translation specification
are mapped into calls to a nonexported action procedure, and the translation
manager fills in parameters based on the event specified on the left-hand
side of a translation.

If MenuPopup is invoked on ButtonPress (possibly
with modifiers), the translation manager pops up the shell with grab_kind
set to XtGrabExclusive and spring_loaded set to True. If MenuPopup
is invoked on EnterWindow (possibly with modifiers), the translation
manager pops up the shell with grab_kind set to XtGrabNonexclusive and
spring_loaded set to False. Otherwise, the translation manager generates
an error. When the widget is popped up, the following actions occur:

Calls
XtCheckSubclassShell.

Generates
an error if the shell's popped_up field is already True.

Calls the callback
procedures on the shell's popup_callback list.

Sets the shell popped_up field
to True and the shell grab_kind and spring_loaded fields appropriately.

If the shell's create_popup_child field is non-NULL, it is called with popup_shell
as the parameter.

(Note that these actions are the same as those
for XtPopup.) MenuPopup tries to find the shell by searching the widget
tree starting at the parent of the widget in which it is invoked. If it
finds a shell with the specified name in the pop-up children of that parent,
it pops up the shell with the appropriate parameters. Otherwise, it moves
up the parent chain as needed. If MenuPopup gets to the application widget
and cannot find a matching shell, it generates an error.